如何从Android中的BaseAdapter完成活动？

Question

Explanation: I know this is my repeated question.Understand the flow of my application. I have multiple fragments in my navigationDrawer when i am in one of my fragment.This fragment call a BaseAdapter adapter and select the value from fragment.After selected an item from my fragment i goes to my mainActivity

Here is my Adapter code

package com.angelnx.angelnx.holidays.adapter;


import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.RadioButton;
import android.widget.TextView;
import android.widget.Toast;

import com.angelnx.angelnx.holidays.Handler.DatabaseHandler;
import com.angelnx.angelnx.holidays.MainActivity;
import com.angelnx.angelnx.holidays.R;
import com.angelnx.angelnx.holidays.model.State;
import com.angelnx.angelnx.holidays.model.Users;

import java.util.List;

public class StateSelectionAdapter extends BaseAdapter{

    private Context context;
    private List<State> state_list;
    private int mselectedVariant;
    private LayoutInflater inflater;
    private DatabaseHandler db;

    public StateSelectionAdapter(Context context,List<State> state_list,int mselectedVariant){
        this.context=context;
        this.state_list=state_list;
        this.mselectedVariant=mselectedVariant;
        inflater=(LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }
    @Override
    public int getCount() {
        return state_list.size();
    }

    @Override
    public Object getItem(int position) {
        return state_list.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    private class Holder{
        TextView state_name;
        RadioButton radioButton;
    }

    @Override
    public View getView(final int position, View convertView, ViewGroup parent) {
        Holder holder=new Holder();

        if(convertView==null){
            convertView=inflater.inflate(R.layout.radiolistviewrow,null);

            holder.state_name=(TextView)convertView.findViewById(R.id.tv_MainText);
            holder.radioButton=(RadioButton)convertView.findViewById(R.id.rb_Choice);

            holder.state_name.setText(this.state_list.get(position).getState_name());
            if(holder.radioButton.isChecked()){

            }
            convertView.setTag(holder);
        }
        else{
            holder=(Holder)convertView.getTag();
        }

        if(position==mselectedVariant){
            holder.radioButton.setChecked(true);
        }
        else{
            holder.radioButton.setChecked(false);
        }

        convertView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                mselectedVariant=position;
                db=new DatabaseHandler(context);

                Users user=new Users();
                user.setId("1");
                user.setSelectState(state_list.get(position).getId());
                int no=db.updateUser(user);
                if(no > 0){
                    Toast.makeText(context, "Your state is:"+state_list.get(position).getState_name(), Toast.LENGTH_SHORT).show();
                }
                else{
                    Toast.makeText(context, "Your state"+state_list.get(position).getState_name(), Toast.LENGTH_SHORT).show();
                }
                StateSelectionAdapter.this.notifyDataSetChanged();
                Intent i=new Intent(context, MainActivity.class);
                i.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP|Intent.FLAG_ACTIVITY_NEW_TASK);
                context.startActivity(i);
                ((Activity)(context)).finish();
            }
        });
        return convertView;
    }
}

Here is an error which i got

FATAL EXCEPTION: main

Process: com.angelnx.angelnx.holidays, PID: 14827
java.lang.ClassCastException: com.angelnx.angelnx.holidays.app.MyApplication cannot be cast to android.app.Activity
at com.angelnx.angelnx.holidays.adapter.StateSelectionAdapter$1.onClick(StateSelectionAdapter.java:105)
at android.view.View.performClick(View.java:4438)
at android.view.View$PerformClick.run(View.java:18422)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)

here is my singleton class namely MyApplication.java

package com.angelnx.angelnx.holidays.app;


import android.app.Application;
import android.content.Intent;
import android.text.TextUtils;

import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.toolbox.Volley;
import com.angelnx.angelnx.holidays.LoginActivity;
import com.angelnx.angelnx.holidays.helper.MyPreferenceManager;

public class MyApplication extends Application{
    public static final String TAG = MyApplication.class
            .getSimpleName();

    private static MyApplication mInstance;
    private RequestQueue mRequestQueue;
    private MyPreferenceManager pref;

    @Override
    public void onCreate() {
        super.onCreate();
        mInstance = this;
    }

    public static synchronized MyApplication getInstance() {
        return mInstance;
    }
    public MyPreferenceManager getPrefManager() {
        if (pref == null) {
            pref = new MyPreferenceManager(this);
        }

        return pref;
    }
    public RequestQueue getRequestQueue() {
        if (mRequestQueue == null) {
            mRequestQueue = Volley.newRequestQueue(getApplicationContext());
        }

        return mRequestQueue;
    }
    public <T> void addToRequestQueue(Request<T> req, String tag) {
        req.setTag(TextUtils.isEmpty(tag) ? TAG : tag);
        getRequestQueue().add(req);
    }

    public <T> void addToRequestQueue(Request<T> req) {
        req.setTag(TAG);
        getRequestQueue().add(req);
    }

    public void cancelPendingRequests(Object tag) {
        if (mRequestQueue != null) {
            mRequestQueue.cancelAll(tag);
        }
    }

}

Answer 1

Pass the Activity reference as a Context in BaseAdapter class. That will work perfectly.

Here you are passing Application reference as Context so the Application is not casting to Activity .

Use the Activity reference where you are creating the instance of this adapter and if you are creating this Adapter in Fragment then use getActivity() method as context.